Obama in Texas: 'You are not alone, you are not forgotten'

4/25/13 5:11 PM EDT

President Obama reprised his role once again as comforter-in-chief Thursday at a moving memorial service for 12 firefighters killed in the fertilizer plant blast in Texas.

"No words adequately describe the courage that was displayed on that deadly night,” Obama said. “What I can do is offer the love and support and prayers of the nation.”

The explosion April 17 killed at least 14 people and injured 200 more. The firefighters had raced to the scene to douse the blaze that preceded the blast.

“We are here to say, 'you are not alone, you are not forgotten,'” Obama said. “We may not all live here in Texas, but we’re neighbors too, we’re Americans, too, and we stand with you and we do not forget. And we’ll be there even after the cameras leave and after the attention turns elsewhere.”

Caskets draped with American flags were lined up next to large photos of the victims at the front of the auditorium, while men and women in uniform filled row after row in the audience – police officers and fellow members of the fire service that had traveled thousands of miles to pay their respects.

The service came exactly one week after Obama played a similar role in Boston, memorializing the victims of the marathon bombings. And the president acknowledged the difficult week

“For this state, for our country, these have been trying and difficult days,” he said, adding that the nation continues to pray for those lost and wounded in Boston. “But know this: while the eyes of the world may have been fixed on places far way, our hearts have also been here in your time of tribulation.”

Investigators have not determined what caused the fire that sparked the explosion of ammonium nitrate at the plant or whether it was intentionally set, although questions are already swirling about what federal regulators did or didn’t do. The AP has reported that OSHA last inspected the plant in 1985.

En route to the memorial in Waco, the president’s helicopter flew over the site, circling the one-time fertilizer plant whose structures are now leveled and the surrounding area, where damage is estimated at $100 milion.

Texas Gov. Rick Perry, who also spoke at the service, saluted the spirit and sacrifice of those who died.

“We will never forget what happened here, nor forget the sacrifices of those who first responded. May God bless you,” he said.

First lady Michelle Obama joined the president at the service, and while she didn’t speak, she did share her thoughts beforehand on Twitter.

“My prayers are with the people of West, TX as we honor the victims of this tragedy. They've shown tremendous courage and resolve. –mo”